Blasters and lasers
Han Solo had it right; "Hokey religions and ancient weapons are no match for a good blaster at your side, kid."
At least, that holds pretty true in the standard AIF universe, even if General Solo might have changed his mind later in his. Sure, there's a lot of exotic weapons available in AIF, both mentioned on the published lists and rare items not mentioned, many of which have some very interesting abilities or properties. But all of them fail to match the overall success of plain blast weapons and lasers, and there are some good reasons why.
Firstly, blasters and lasers in contemporary AIF run on tireless little microfusion cells, so you get to just keep squeezing the trigger until you don't want to any more or until you die. This is an automatic leg up over all the exotic projectile weapons, as they invariably have a finite number of rounds to fire.
Secondly, there's the ubiquitousness of lasers and blasters - they're found everywhere in known space. This means that if you've trained in the use of a blaster pistol or blast rifle, and you happen to lose yours, you can find another one pretty easily no matter where you are. If you're trained primarily to use the deadly and rare HipGun of Wikkem-Ti, you better plan a trip to Wikkem space if your HipGun tragically goes missing. Technically there's also an advantage for keeping a low profile by using unremarkable equipment, but since most adventurers don't tend to have much real proclivity for that I won't bother mentioning it.
Thirdly, lasers and blasters are comparatively simple technology. This means that any techie with a pocket knife and a coat hanger can fabricate one. This also means that they tend to be rather cost-effective, compared to other kinds of weapons with special properties or abilities. Many beings make much of the frightening capacity for plasma weapons to eat through anything, including armour, but since personnel energy shields are looking to be the new standard instead of physical armour, all plasma is really good for is hitting innocent beings behind your intended target, in addition to burning through your credits.
The last reason is a purely philosophical one. Exotic and upgraded weapons are really a kind of crutch, and have the tendency to be relied on too much. A being that is accustomed to the power and abilities of certain kind of weapon will often fail recognize how much of their overall effectiveness is based on their equipment. An overconfident being that is deprived of their vaunted weapon often becomes easy prey. Typically, the only ones that get to keep scary weaponry in AIF are the beings that don't really need them in order to be scary.